FEATURE: Add Instant Run-off Voting to Poll Plugin (Part 1: migrate existing plugin to Glimmer only) (#27204)

The "migration to Glimmer" has been broken out here from #27155 to make the review process less onerous and reduce change risk: 

* DEV: migrates most of the widget code to Glimmer in prep for IRV additions
* NB This already incorporates significant amounts of review and feedback from the prior PR.
* NB because there was significant additional feedback relating to older Poll code that I've improved with feedback, there are some additional changes here that are general improvements to the plugin and not specific to IRV nor Glimmer!
* There should be no trace of IRV code here.

Once this is finalised and merged we can continue to progress with #27155.

plugins/poll/lib/poll.rb

@@ -1,6 +1,9 @@
 # frozen_string_literal: true
 
 class DiscoursePoll::Poll
+  MULTIPLE = "multiple"
+  REGULAR = "regular"
+
   def self.vote(user, post_id, poll_name, options)
     poll_id = nil
 
@@ -9,6 +12,7 @@ class DiscoursePoll::Poll
         poll_id = poll.id
         # remove options that aren't available in the poll
         available_options = poll.poll_options.map { |o| o.digest }.to_set
+
         options.select! { |o| available_options.include?(o) }
 
         if options.empty?
@@ -35,17 +39,21 @@ class DiscoursePoll::Poll
         PollVote.where(poll: poll, user: user).where.not(poll_option_id: new_option_ids).delete_all
 
         # create missing votes
-        (new_option_ids - old_option_ids).each do |option_id|
+        creation_set = new_option_ids - old_option_ids
+
+        creation_set.each do |option_id|
           PollVote.create!(poll: poll, user: user, poll_option_id: option_id)
         end
       end
 
     # Ensure consistency here as we do not have a unique index to limit the
     # number of votes per the poll's configuration.
-    is_multiple = serialized_poll[:type] == "multiple"
+    is_multiple = serialized_poll[:type] == MULTIPLE
     offset = is_multiple ? (serialized_poll[:max] || serialized_poll[:options].length) : 1
 
-    DB.query(<<~SQL, poll_id: poll_id, user_id: user.id, offset: offset)
+    params = { poll_id: poll_id, offset: offset, user_id: user.id }
+
+    DB.query(<<~SQL, params)
     DELETE FROM poll_votes
     USING (
       SELECT
@@ -61,6 +69,18 @@ class DiscoursePoll::Poll
     AND poll_votes.user_id = to_delete_poll_votes.user_id
     SQL
 
+    if serialized_poll[:type] == MULTIPLE
+      serialized_poll[:options].each do |option|
+        option.merge!(
+          chosen:
+            PollVote
+              .joins(:poll_option)
+              .where(poll_options: { digest: option[:id] }, user_id: user.id, poll_id: poll_id)
+              .exists?,
+        )
+      end
+    end
+
     [serialized_poll, options]
   end
 
@@ -159,7 +179,9 @@ class DiscoursePoll::Poll
 
       result = { option_digest => user_hashes }
     else
-      votes = DB.query <<~SQL
+      params = { poll_id: poll.id, offset: offset, offset_plus_limit: offset + limit }
+
+      votes = DB.query(<<~SQL, params)
         SELECT digest, user_id
           FROM (
             SELECT digest
@@ -167,10 +189,10 @@ class DiscoursePoll::Poll
                   , ROW_NUMBER() OVER (PARTITION BY poll_option_id ORDER BY pv.created_at) AS row
               FROM poll_votes pv
               JOIN poll_options po ON pv.poll_option_id = po.id
-              WHERE pv.poll_id = #{poll.id}
-                AND po.poll_id = #{poll.id}
+              WHERE pv.poll_id = :poll_id
+                AND po.poll_id = :poll_id
           ) v
-          WHERE row BETWEEN #{offset} AND #{offset + limit}
+          WHERE row BETWEEN :offset AND :offset_plus_limit
       SQL
 
       user_ids = votes.map(&:user_id).uniq
@@ -292,7 +314,7 @@ class DiscoursePoll::Poll
         post_id: post_id,
         name: poll["name"].presence || "poll",
         close_at: close_at,
-        type: poll["type"].presence || "regular",
+        type: poll["type"].presence || REGULAR,
         status: poll["status"].presence || "open",
         visibility: poll["public"] == "true" ? "everyone" : "secret",
         title: poll["title"],